Etching technology is frequently utilized for removing one or more materials during a variety of technical fabrication processing including, for example, semiconductor processing. In many applications an etch chemistry is chosen to selectively remove a first material relative to a second material. An etch is considered to be selective for a first material relative to a second material (or to be selective to the second material) if the etch removes the first material at a faster rate than the second material.
During semiconductor processing, wet etch techniques are commonly utilized to isotropically etch dielectric materials selectively relative to silicon materials. Wet etchants for isotropic oxide removal include etchants referred to as buffered oxide etchants (BOEs). Although such etchants are highly selective to silicon, some silicon etching can occur during the wet etch process. The slow etching of Si which occurs during wet etch processing can result in roughening of silicon surfaces, or unintentional thinning or removal of silicon materials. For example, removal of a gate oxide material during semiconductor fabrication can result in roughening of an underlying silicon surface which can ultimately compromise gate oxide integrity and/or tunneling oxide properties. Additional problems can arise during memory array formation where wet etch processing is utilized to remove dielectric materials within the array area near the periphery. Specifically, unintentional removal of a protective silicon material can expose dielectric material in the periphery leading to periphery blowout, where the term “blowout” refers to unintentional etching of material.
It is desirable to develop alternative etchant compositions and methods of processing substrates and semiconductor constructions.